Add sync error logging, extend error flash, fix unload saves

- Log workforce sync errors to backend stdout so they appear in docker logs
- Extend error flash from 5s to 15s so errors are readable
- Replace sendBeacon (POST-only) with keepalive fetch (PUT) on unload —
  sendBeacon was hitting 404s on all three unload saves

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/lucide-react/dist/esm/icons/weight-tilde.mjs

@@ -0,0 +1,24 @@
+/**
+ * @license lucide-react v1.24.0 - ISC
+ *
+ * This source code is licensed under the ISC license.
+ * See the LICENSE file in the root directory of this source tree.
+ */
+
+import createLucideIcon from '../createLucideIcon.mjs';
+
+const __iconNode = [
+  [
+    "path",
+    {
+      d: "M6.5 8a2 2 0 0 0-1.906 1.46L2.1 18.5A2 2 0 0 0 4 21h16a2 2 0 0 0 1.925-2.54L19.4 9.5A2 2 0 0 0 17.48 8z",
+      key: "1wl739"
+    }
+  ],
+  ["path", { d: "M7.999 15a2.5 2.5 0 0 1 4 0 2.5 2.5 0 0 0 4 0", key: "1egezo" }],
+  ["circle", { cx: "12", cy: "5", r: "3", key: "rqqgnr" }]
+];
+const WeightTilde = createLucideIcon("weight-tilde", __iconNode);
+
+export { __iconNode, WeightTilde as default };
+//# sourceMappingURL=weight-tilde.mjs.map